fix: fixes an issue where the package_path was not passed to netlify/build

[lukasholzer]

…build for config mutations

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Summary

Fixes an issue where netlify build did not receive the package path and failed reading the config file for mutations on build plugins.

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[github-actions]

📊 Benchmark results

Comparing with b381412

• Dependency count: 1,313 (no change)
• Package size: 271 MB (no change)